1. Field of the Invention
The present invention relates to a scroll compressor, and particularly, to a scroll compressor including a protecting device which is able to control temperature in the compressor, as well as to control pressure in the compressor.
2. Description of the Background Art
Generally, various types of compressors can be used according to compressing methods, and a scroll compressor is mainly used for an air conditioner which needs to be small and light weight.
FIG. 1 is a cross-sectional view showing a scroll compressor including a pressure protecting device according to the conventional art.
The scroll compressor according to the conventional art comprises: a casing 106 having a hermetic space and connected a suction pipe 102 for sucking a fluid and a discharge pipe 104 are for discharging compressed fluid respectively; a driving unit 108 disposed on a lower part of the casing 106 for generating a driving force; and a compressed unit 110 disposed on an upper part of the casing 106 and connected to the driving unit 108 by a rotating shaft 112 for compressing the fluid sucked through the suction pipe 102 and for discharging the compressed fluid to the discharging pipe 104.
A supporting frame 114 for supporting the rotating shaft 112 to be rotatable and supporting the compressed unit 110 is installed in the casing 106, and a separating panel 120 is installed in the casing 106 to divide the inner area of the casing 106 into a first chamber 116 for maintained a low pressure state and a second chamber 118 for maintained a high pressure state.
The driving unit 108 comprises a stator 122 fixed toward a boundary direction of the casing 106, and a rotor 124 disposed on an inner circumferential surface of the stator 122 and fixed on the rotating shaft 112. In addition, when an electric power is applied to the stator 122, the rotor 124 is rotated by an interaction between the stator 122 and the rotor 124 to rotate the rotating shaft 112.
The compressed unit 110 includes a fixed scroll 128 having a fixed vane 126 of an involute form and fixed on the separating panel 120; and an orbiting scroll 132 having an orbiting vane 130 of an involute form corresponding to the fixed vane 126 so that a predetermined compressing chamber is formed between the fixed vane 126 and the orbiting vane 130, supported by the supporting frame 114 so as to orbit and orbited when the rotating shaft rotates.
A discharging passage 136 through which the fluid compressed by the interaction between the fixed vane 126 and the orbiting vane 130 is discharged toward the second chamber 118 is formed on a center part of the fixed scrolled 128, and a check valve 138 for preventing the fluid discharged into the second chamber 118 from flowing backward the first chamber 116 is installed on an upper part of the discharging passage 136.
The check valve 138 includes a valve body 142, which is fixed on a central upper end of the fixed scroll 128 on which the discharging passage 136 is formed and has a penetrated center part so as to be connected to the discharging passage 136, and a valve member 144 of a piston type inserted on an inner side of the valve body 142 so as to move in up-and-down direction for blocking the discharging passage 136 by the self weight.
In addition, a pressure protecting device (A) for by-passing the fluid of high pressure in the second chamber 118 to the first chamber 116 in case that the pressure difference between the first and the second chambers 116 and 118 is larger than a predetermined value or in case that the pressure in the first chamber 116 is too low is installed on one side of the separating panel 120.
As shown in FIG. 2, the pressure protecting device (A) comprises: a cylinder 150 for connecting the first chamber 116 and the second chamber 118; a piston 152 for opening/closing the cylinder 150 as moving in up-and-down direction inside the cylinder 150; and a spring 154 disposed between one side surface of the piston 152 and the inner wall of the cylinder 150 for providing the piston 152 with a certain elastic force.
The cylinder 150 is fixed on one side of the separating panel 120, and bypass flow passages 156 through which the fluid of high pressure in the second chamber 118 is by-passed to the first chamber 116 are formed on an upper and lower parts of the cylinder 150.
The upper surface of the piston 152 is disposed to adhere to the bypass flow passage 156, and the elastic member 154 is disposed between the lower surface of the piston 152 and the inner wall of the cylinder 150 to provide the piston 152 with the elastic force by which the bypass flow passage 156 is closed.
Operation of the pressure protecting device in the scroll compressor according to the conventional art will be described as follows.
FIG. 3 is a view showing an operational status of the pressure protecting device in the scroll compressor according to the conventional art.
In case that the operational range of the compressor is normal, when the electric source is applied to the driving unit 108, the rotating shaft 112 rotates to orbit the orbiting scroll 132, and the fluid sucked into the first chamber 116 through the suction pipe 102 is compressed by the interaction between the orbiting vane 130 and the fixed vane 126. In addition, the compressed fluid is flowed into the second chamber 118 and discharged to outer side through the discharging pipe 104.
During the operation of the compressor as described above, if the pressure difference between the first chamber 116 and the second chamber 118 is larger than a predetermined value or if the pressure in the first chamber 116 is lower than a predetermined level, the pressure protecting device is operated to provide the first chamber 116 with the fluid of high pressure in the second chamber 118, and thereby, the pressure difference between the first chamber 116 and the second chamber 118 is maintained to be an appropriate level.
That is, when the pressure difference between the first chamber 116 and the second chamber 118 becomes larger than pre-set value, the piston 152 moves downward as overcoming the elastic force of the spring 154 by the pressure of the high pressure fluid in the second chamber 118. Then, the bypass flow passage 156 is opened, and the fluid of high pressure in the second chamber 118 is by-passed to the first chamber 116 to maintain the pressure of the fluid in the first and second chambers 116 and 118 to be the set status.
FIG. 4 is a cross-sectional view showing a state that a temperature protecting device is installed on the scroll compressor according to the conventional art, and FIG. 5 is a cross-sectional view showing the temperature protecting device according to the conventional art.
The temperature protecting device (B) comprises: a bypass hole 170 penetrating between the first chamber 116 and the second chamber 118 formed on one side of the separating panel 120; a thermo-disk 172 disposed on an upper surface of the bypass hole 170; and a cover 174 for supporting both ends of the thermo-disk 172 fixed in the boundary direction of an upper part of the bypass hole 170. Herein, the thermo-disk is formed as overlapping two members having different thermal deformation rates, and a through hole 176 through which the fluid passes is formed on an upper part of the cover 174.
FIG. 6 is a view showing an operational status of the temperature protecting device according to the conventional art.
The temperature protecting device (B) maintains the state that the thermo-disk 172 blocks the bypass hole 170 when the compressor is normally operated, and when the temperature in the second chamber 118 is larger than a set value, the thermo-disk is distorted by the heat to open the bypass hole 170. Then the fluid in the second chamber 118 is by-passed to the first chamber 116 through the bypass hole 170 to decrease the temperature in the second chamber 118. At that time, when the temperature becomes lower than the set value, the thermo-disk is returned to the original state to block the bypass hole 170.
However, according to the protecting device in the scroll compressor of the conventional art, in case that only the pressure protecting device is installed, the protection according to the temperature change in the compressor can not be made. In addition, when only the temperature compensating device is installed, the protection according to the pressure change in the compressor can not be made. In case that the pressure and the temperature protecting devices are disposed, the structure of the compressor becomes complex and the production cost is increased.
Also, according to the conventional pressure protecting device, when the piston is moved by the pressure difference between the first and the second chambers and the bypass flow passage is opened, the fluid of high pressure in the second chamber is by-passed to the first chamber at once. Therefore, the pressure in the first chamber is risen rapidly, and thereby, the reliability of the compressor is lowered and an error may be generated.
Therefore, an object of the present invention is to provide a scroll compressor which can be protected when the compressor is in abnormal pressure or abnormal temperature status, and of which a structure can be made simple and production cost can be reduced.
Another object of the present invention is to provide a scroll compressor by which a phenomenon that an internal pressure is changed rapidly can be reduced, and thereby a reliability of the compressor is improved and a damage in the compressor can be prevented.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a sealed casing including a first chamber for forming low pressure and a second chamber for forming high pressure which are divided by a separating panel; a driving unit built-in the casing for generating a driving force; a compressed unit connected to the driving unit via a rotating shaft for compressing and discharging fluid when the driving unit is operated; and a protecting device installed on one side of the separating panel for by-passing the fluid of high pressure or high temperature in the second chamber to the first chamber when a pressure difference or a temperature difference between the first and the second chambers becomes larger than a set value.
The protecting device in the scroll compressor according to the present invention comprises: a shell which fixed on one side of the separating panel so as to connect the first chamber and the second chamber and includes an suction passage and a discharging passage formed on an upper and a lower parts; a thermal deformation member disposed in the shell so as to be moved in up-and-down direction for opening/closing the suction passage; and an elastic member disposed between a lower surface of the thermal deformation member and an inner wall surface of the shell for providing the thermal deformation member with a certain elastic force.
The shell in the scroll compressor according to the present invention is fixed on a through hole formed on one side of the separating panel, a plurality of suction passages through which the fluid of high pressure in the first chamber is flowed are formed on an upper surface of the shell located on the first chamber side, and a discharging passage through which the fluid passed through the shell is discharged toward the first chamber is formed on a lower surface which is located on the second chamber side.
The upper surface of the shell in the scroll compressor according to the present invention is formed concavely, that is, the center part of the shell is depressed.
The shell in the scroll compressor according to the present invention is formed as a cone in which an area through which the fluid passes is enlarged as going to the first chamber from the second chamber.
The thermal deformation member in the scroll compressor according to the present invention is formed as a concave plate so as to adhere to the suction passage of the shell and to close the suction passage, and formed using a material which is distorted when it is heated more than a predetermined level.
The elastic member in the scroll compressor according to the present invention is formed as a conical coil spring.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.